Processes of agglomeration and coagulation of micro- and nano-particles and formation of thin films by direct deposition of nanoparticles from aqueous solutions on the substrate particles (coating process) are studied. It is shown that both chemical composition of the solution and details of the suspension flow affect the process. To account for these effects the Batchelor model of microflow and the Gouy-Stern-Grahame double-layer model together with the Nernst equation for the surface potential are used. Results of modeling are applied to interpret several experimental observations including coagulation of micro- and nano-particles, agglomeration of nano-particles and coating with nano-particles. Relevance of proposed method of modeling to industrial problems is presented and discussed. (c) 2004 Elsevier Ltd. All rights reserved.